A threshold analysis of the cost-effectiveness of artemisinin-based combination therapies in sub-Saharan Africa
A threshold analysis of the cost-effectiveness of artemisinin-based combination therapies in sub-Saharan Africa
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DOI：
10.4269/ajtmh.2004.71.196
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发表时间：
2004-08-01
影响因子：
3.3
通讯作者：
Mills, AJ
中科院分区：
文献类型：
--
作者：
Coleman, PG;Morel, C;Mills, AJ
人们普遍认为，青蒿素类复方疗法对于解决撒哈拉以南非洲抗疟药耐药性发展所造成的日益严重的问题至关重要。然而，新的青蒿素综合疗法的成本可能比目前的疗法高得多。因此，在倡导改变政策之前，必须正式审查更有效但更昂贵的青蒿素综合疗法的成本效益。重要的是，任何这样的经济评估都必须考虑耐药性的时间动态，而不仅仅关注在目前的耐药性水平下今天转换是否具有成本效益的静态问题，特别是因为未来新抗疟药物的开发是如此不确定。然而，预测耐药性的未来变化是准确量化随时间推移与不同药物治疗相关的相对成本和健康结果的主要困难。在这里，我们使用一个简单的决策树模型来估计增量成本效益使用ACT相比，坚持与目前的治疗，超过5年，10年，15年的时间。我们使用一般的逻辑增长函数来描述耐药性的动态，其中耐药性的起始频率和最大生长可能会改变。然而，我们并没有假设ACT耐药的绝对增长率，而是允许ACT耐药增长率相对于当前治疗的增长率的比率发生变化。以这种方式定义ACT耐药性的增长率使我们能够计算ACT不再具有成本效益的阈值比率，对于任何对当前疗法和ACT的耐药性的起始条件，以及在任何时间段内。其他决策树参数的不确定性对阈值比率值的影响也被量化，使用蒙特卡罗模拟技术。这项分析表明，在大多数情况下，青蒿素综合疗法具有成本效益的可能性超过95%，但对磺胺嘧啶/乙胺嘧啶的初始耐药性水平很低，而且需要五年时间。这些预测是保守的，因为95%的确定性是支持拒绝新策略的严格决策规则。讨论了未包括在分析结果稳健性中的其他变量的重要性（例如，考虑到有疟疾风险的整个人口、青蒿素综合疗法在特定环境中的可负担性以及根据人口遗传参数建立的抗药性增长模型）。
Artemisinin-based combination therapies (ACTs) are generally regarded as vital in addressing the growing problem posed by the development of antimalarial resistance across sub-Saharan Africa. However, the costs of the new ACTs are likely to be significantly higher than current therapies. Therefore, it is important to examine formally the cost-effectiveness of the more effective yet more expensive ACTs before advocating a switch in policy. Importantly, any such economic evaluation must consider the temporal dynamics of drug resistance, and not just focus on the static question of whether switching today would be cost-effective at current levels of resistance, particularly since the development of new antimalarials in the future is so uncertain. However, predicting the future changes in drug resistance is a major difficulty in accurately quantifying the relative costs and health outcomes associated with different drug therapies over time. Here, we use a simple decision tree model to estimate the incremental cost-effectiveness of using ACTs, compared with persisting with current therapies, over 5-, 10-, and 15-year periods. We describe the dynamics of drug resistance using a general logistic growth function, in which the starting frequency of resistance and maximum growth may be altered. However, rather than make assumptions about the absolute rate at which resistance to ACTs will progress, we allow the ratio of the growth rate of resistance to ACTs relative to that of current therapies to vary. Defining the growth rate of ACT resistance in this manner allows us to calculate the threshold ratio at which ACTs would no longer appear cost-effective, for any starting conditions of resistance to current therapies and ACTs, and over any time period. The influence of uncertainty in other decision tree parameters on the threshold ratio values is also quantified, using Monte Carlo simulation techniques. This analysis shows that ACTs are more than 95% likely to be cost-effective under most conditions, other than very low levels of initial resistance to sulfadoxine/pyrimethamine and a five-year time frame. These predictions are conservative in that 95% certainty is a stringent decision rule favoring the rejection of new policies. The importance of other variables not included in the analysis for the robustness of the findings are discussed (e.g., consideration of the entire population at risk for malaria, the affordability of ACTs in specific settings, and the growth of resistance modeled according to population genetic parameters).